Ammonia Nitrogen Excretion Research Articles

Ammonia excretion in the neotenous newt, Necturus maculosus (rafinesque)

1. 1. Necturus was found to be ammonotelic. The skin serves as the main route of ammonia excretion. Gill ligation did not appreciably alter the rate of ammonia nitrogen excretion. Approximately 10 per cent of the total ammonia plus urea nitrogen is eliminated by the kidneys. 2. 2. In vitro experiments with isolated skin have shown that ammonia diffuses from the internal bathing fluid outward; the rate of diffusion proceeds linearly with respect to time. Values calculated for in vitro ammonia excretory rates are similar to the experimentally determined in vivo rates. 3. 3. Blood ammonia nitrogen in normal Necturi averaged 0.44 μatom/ml. After immersion of Necturus in a solution containing 1 μatom/ml ammonia nitrogen, the excretory rate increased fourfold over the control and blood ammonia nitrogen doubled in value. There was no increase in urea excretion. 4. 4. The amino acids l-glutamine and l-alanine were not deaminated by the isolated skin. A central site of ammonia production was indicated.

Variations in Alkali Reserve of Plasma and Excretion of Total Titratable Urinary Acid in Hyperthyroidism

SummarySerial observations on 18 patients reveal a rise of carbon dioxide-combining power of the plasma in 8 cases as their clinical status improves with treatment and operation. All values fall within the normal range. The excretion of total titratable acid of the urine in 9 patients on constant diets is reported. In the patients in whom decided improvement occurs shortly after operation, the preoperative amounts are from 2 to 4 times as large as those excreted postoperatively. Excretion of organic acids and ammonia nitrogen were also followed for nearly a month in one patient and in exacerbations of hyperthyroidism her excretion of these substances, as well as of total acid, is seen to rise; urinary pH values fall during exacerbations. In 2 patients who improved promptly following thyroidec-tomy, fall in total acid excretion is accompanied by a rise of alkali reserve; in a third patient who showed little early improvement and only a slight change of total acid excretion, there was no change in carbon di...

Observations on the mineral metabolism of pullets. II

1. Where heavy phosphorus excretion accompanies egg laying in the pullet the excretion of ammonia nitrogen is simultaneously increased. It is probable that this indicates an excretion of excess phosphate in the urine as ammonium phosphate.2. It is shown that heavy phosphorus excretion does not accompany egg laying provided the calcium carbonate intake is sufficiently high.3. The origin of the excess of phosphorus excretion is discussed in relation to calcium-phosphorus metabolism.4. Pullets on a ration containing 5 per cent, calcium carbonate laid eggs containing a higher percentage of P2O5than pullets receiving a similar ration but from which the calcium carbonate supplement was omitted.5. Some evidence is put forward in support of the view that current standards pitch the requirements of digestible protein for egg production at too high a level.